The leading edge of propeller blade requires protection from erosion, lightning and foreign objects. A nickel sheath is disposed upon the leading edge of the blade to provide such protection. The nickel sheath is also designed to withstand normal bending moments experienced by the propeller blade.
The nickel sheath is typically constructed by electroforming nickel particles upon a titanium die the blade. Nickel in solution is deposited on the die, which acts as a cathode, to form the sheath.
Portions of the external surface of the die are covered with a fiberglass casing. The casing ensures that the sheath is electroformed on the uncovered external surface of the die as desired. A portion of the external surface of the die beyond the desired blueprint dimension of the sheath is left uncased.
A line corresponding to the desired dimension of the sheath is scribed within the uncovered external surface of the die. The line is known to leave an imprint within the nickel electroformed thereover. The die is then deposited in a nickel bath, subjected to electric current to electroform the nickel sheath thereupon, and then removed from the bath. The sheath is removed from the die and machined to the scribe line.